4 files changed, 103 insertions, 1 deletions

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 94c4c8b5cb8f..19036cdbed8f 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -286,4 +286,53 @@ static inline int vma_pkey(struct vm_area_struct *vma)
 	return pkey;
 }
 
+static inline bool __pkru_allows_pkey(u16 pkey, bool write)
+{
+	u32 pkru = read_pkru();
+
+	if (!__pkru_allows_read(pkru, pkey))
+		return false;
+	if (write && !__pkru_allows_write(pkru, pkey))
+		return false;
+
+	return true;
+}
+
+/*
+ * We only want to enforce protection keys on the current process
+ * because we effectively have no access to PKRU for other
+ * processes or any way to tell *which * PKRU in a threaded
+ * process we could use.
+ *
+ * So do not enforce things if the VMA is not from the current
+ * mm, or if we are in a kernel thread.
+ */
+static inline bool vma_is_foreign(struct vm_area_struct *vma)
+{
+	if (!current->mm)
+		return true;
+	/*
+	 * Should PKRU be enforced on the access to this VMA?  If
+	 * the VMA is from another process, then PKRU has no
+	 * relevance and should not be enforced.
+	 */
+	if (current->mm != vma->vm_mm)
+		return true;
+
+	return false;
+}
+
+static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write)
+{
+	/* allow access if the VMA is not one from this process */
+	if (vma_is_foreign(vma))
+		return true;
+	return __pkru_allows_pkey(vma_pkey(vma), write);
+}
+
+static inline bool arch_pte_access_permitted(pte_t pte, bool write)
+{
+	return __pkru_allows_pkey(pte_flags_pkey(pte_flags(pte)), write);
+}
+
 #endif /* _ASM_X86_MMU_CONTEXT_H */
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index e997dcc6ee2b..3cbfae80abb2 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -919,6 +919,35 @@ static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
 }
 #endif
 
+#define PKRU_AD_BIT 0x1
+#define PKRU_WD_BIT 0x2
+
+static inline bool __pkru_allows_read(u32 pkru, u16 pkey)
+{
+	int pkru_pkey_bits = pkey * 2;
+	return !(pkru & (PKRU_AD_BIT << pkru_pkey_bits));
+}
+
+static inline bool __pkru_allows_write(u32 pkru, u16 pkey)
+{
+	int pkru_pkey_bits = pkey * 2;
+	/*
+	 * Access-disable disables writes too so we need to check
+	 * both bits here.
+	 */
+	return !(pkru & ((PKRU_AD_BIT|PKRU_WD_BIT) << pkru_pkey_bits));
+}
+
+static inline u16 pte_flags_pkey(unsigned long pte_flags)
+{
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+	/* ifdef to avoid doing 59-bit shift on 32-bit values */
+	return (pte_flags & _PAGE_PKEY_MASK) >> _PAGE_BIT_PKEY_BIT0;
+#else
+	return 0;
+#endif
+}
+
 #include <asm-generic/pgtable.h>
 #endif	/* __ASSEMBLY__ */
 
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 6e71dcf699ab..319331afae24 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -897,6 +897,16 @@ bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address)
 	__bad_area(regs, error_code, address, NULL, SEGV_MAPERR);
 }
 
+static inline bool bad_area_access_from_pkeys(unsigned long error_code,
+		struct vm_area_struct *vma)
+{
+	if (!boot_cpu_has(X86_FEATURE_OSPKE))
+		return false;
+	if (error_code & PF_PK)
+		return true;
+	return false;
+}
+
 static noinline void
 bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
 		      unsigned long address, struct vm_area_struct *vma)
@@ -906,7 +916,7 @@ bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
 	 * But, doing it this way allows compiler optimizations
 	 * if pkeys are compiled out.
 	 */
-	if (boot_cpu_has(X86_FEATURE_OSPKE) && (error_code & PF_PK))
+	if (bad_area_access_from_pkeys(error_code, vma))
 		__bad_area(regs, error_code, address, vma, SEGV_PKUERR);
 	else
 		__bad_area(regs, error_code, address, vma, SEGV_ACCERR);
@@ -1081,6 +1091,15 @@ int show_unhandled_signals = 1;
 static inline int
 access_error(unsigned long error_code, struct vm_area_struct *vma)
 {
+	/*
+	 * Access or read was blocked by protection keys. We do
+	 * this check before any others because we do not want
+	 * to, for instance, confuse a protection-key-denied
+	 * write with one for which we should do a COW.
+	 */
+	if (error_code & PF_PK)
+		return 1;
+
 	if (error_code & PF_WRITE) {
 		/* write, present and write, not present: */
 		if (unlikely(!(vma->vm_flags & VM_WRITE)))
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 2f0a32945cda..bab259e75984 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -11,6 +11,7 @@
 #include <linux/swap.h>
 #include <linux/memremap.h>
 
+#include <asm/mmu_context.h>
 #include <asm/pgtable.h>
 
 static inline pte_t gup_get_pte(pte_t *ptep)
@@ -89,6 +90,10 @@ static inline int pte_allows_gup(unsigned long pteval, int write)
 	if ((pteval & need_pte_bits) != need_pte_bits)
 		return 0;
 
+	/* Check memory protection keys permissions. */
+	if (!__pkru_allows_pkey(pte_flags_pkey(pteval), write))
+		return 0;
+
 	return 1;
 }